The main point of that is the idea that humans err. All humans err. We all make mistakes, and we all intentionally do wrong. It's just the way things go. Now, suppose for a moment that you choose to never again make a mistake or do anything wrong. Do you think that it would work? Of course not. We cannot always keep ourselves from stumbling. There is only One Being who can.
"Now to Him who is able to keep you from stumbling, and to present you faultless, before the presence of His glory with exceeding joy..."
That's right. God is only one who can keep us from falling from anything. So, supposing that it is possible to fall from salvation, we are not able to keep ourselves from falling, but who is? God. So, if God is able to keep us from falling away from salvation, will He?
"...being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ"
For those of us who have turned to Christ for salvation, God has chosen graciously to hear our cry and save us. He has begun a good work in our lives, He has begun conforming us into the image of His Son. Here in this verse we have His promise that if He has begun the work of sanctification in our lives, that He will complete it. We have His Word. He's not just going to let us fall off the map. He will never give up working good in us, and since we are adopted as His children, He will also work good in us by disciplining us.
"If you endure chastening, God deals with you as with sons; for what son is there whom a father does not chasten?"
If you had a son, you would not let him fall off a cliff to his death, if you could prevent it, would you? Of course you wouldn't!
Matthew 7:11Not only is God the only One powerful enough to keep us from falling, but if we ask Him to save us, then we have His loving fatherly promise to see us through to the end and to discipline us when we get off-track.
"If you then, being evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask Him!"
Speaking of us being in God's family, the Bible teaches that we, as christians, are in fact adopted. God is now our Father.
"For you did not receive the spirit of bondage again to fear, but you received the Spirit of adoption by whom we cry out, 'Abba, Father.'"
The interesting thing about having a father is that he will always be your dad! I'd like to also bring up this very awesome fact about the whole adoption deal: "as I have looked at 1st century Roman adoption, as well as modern adoption I note that one may disinherit a child born to a family physically, but legally one may not disinherit a child who has been adopted." (LinkToQuotedWebsite) This is God's part of the deal. We feebly ask for help, which accomplishes nothing, but God in love and power adopts us, and vows never to leave us. (Hebrews 13:5) He says that He has adopted us as sons, and He will not disinherit us.
Another part of God's dealings with us is His Seal upon us. I've already discussed that we have His promise. But not only do we have God's promise, but also we has His Seal on us. What do I mean by that?
"And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption."
We are sealed by the Holy Spirit, who is God Almighty, until we fall away. Wait. No. That's not what it said. It said we are sealed until the day of redemption. Not even the say of judgment and condemnation, but the final day of our redemption. Awesome! Now, in today's culture of twitter, email, and fed-ex, we've kinda lost sight of what a "seal" is. In the olden days, they didn't lick envelopes to close them. They would put wax or something on it, and put their metal seal on top of that, to help the wax take shape as their seal. It would not only emphasize the authority of the person who sealed it, as when a king would give his side-kick the royal signet ring, but also prevented tampering before it reached the proper destination.
"This seal that the Holy Spirit places upon us reflects the long usage of the signet ring by royalty. The seal of would indicate that the contents were not to be tampered with except by authorized persons, until the communication or container arrived at its destination. It was a sign of ownership (2 Tim. 2:19) and security. Interestingly, the same word is used for the seal set upon Satan in the bottomless pit in Rev. 20:3." The purpose of the seal was “so that he should deceive the nations no more till the thousand years were finished.” This is directly comparable to our sealing: same God, same purpose (until the intended time), same security. Satan will not be able to get out, will he? Neither will the Christian be able to “get out” of salvation. Thank God that our salvation is life and blessing, instead of death and punishment.
Finally, I love these verses, it just really sums things up really well:
2 Timothy 2:12-13
" If we deny Him,
He also will deny us.
If we are faithless,
He remains faithful;
He cannot deny Himself."
If we say "no" to God, He will say "no" to our requests. But when we are faithless and would fall away, God will never let us go. He cannot say "no" to Himself, to his own promises.
There is only one who can keep us from falling off of life's cliffs, and because He is an awesome and loving person, when we ask for help, He's actually willing to give us that help that we ask for. He has adopted us into His family, and works good in us until the day when we meet Him face to face. In addition to His promises, which are in some people's mind only words, He has sealed us with an unbreakable seal, until the day of redemption. It does not rely on us, but it depends on God to save us, to continue to save us, and to present us faultless in the end. And inasmuch as it relies on God, we can rest safely, knowing that though we might fail, God will not.